Wms Sys 11 PIA(all) issue (Leons)

Scucci

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I'm working on a friends Road Kings MPU right now... severe battery damage. I've repaired everything I saw. I'm working with Leon's test ROM now, just pulsing the PIAs. PA1 and PB1 are stuck(high) on all PIAs... I don't know enough (or anything really) about the workings on 6821 PIAs. What am I missing that would effect PA1 (pin3) and PB1 (pin11) ?
 
PA1/PB1 stuck high across all PIAs usually means you've still got corrosion bridging to +5 or open traces from the battery damage. Check continuity from those pins to +5 and ground, and inspect the resistor packs and vias near the battery area. If the lines stay high with the PIAs pulled, it's a short; if they drop, bad PIAs. Clean thoroughly, reflow, and socket if needed.
 
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